Service-observing apparatus for automatic telephone systems



- Aug. 23, 1927.

F. T. MADSEN SERVICE OBSERVING APPARATUS FOR AUTOMATIC TELEPHONE SYSTEMS eat 1 Original Filed July 15, 1922 5 Shee -Inusr a urred TIM arisen Z.

Aug. 23,1927. 1,640,085

F. T. MA'DSEN SERVICE OBSERVING APPARATUS FOR AUTOMATIC TELEPHONE SYSTEMS Original Filed July 15, 1922 5 Sheets-Sheet 2 w, //3/ 7% [:li L

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- Aug. 23,1927. 1,640,085

F. T. MADSEN SERVICE OBSERVING APPARATUS FOR AUTOMATIC TELEPHONE SYSTEMS Orizinr-U pnpa' hn 1'5 1922 5 Sheets-Sheet 5 w l Imr5n 1:11:

Fred El i 555511 Z.df.-4fm

I 7 1,640,085 ,A g- 1927' F. T. MADSEN SERVICE OBSERVING APPARATUS FOR AUTOMATIC TELEPHONE SYSTEMS Origina Filed July 15, 1922 5 Sheets-Sheet 4 :{IHI

Iwan'rfif- Fred T. Hadsan %Z'MMF Aug. 23 1927.

F. T. MADSEN SERVICE OBSERVING APPARATUS FOR AUTOMATIC TELEPHONE SYSTEMS 5 Sheets-Sheet 5 Fired T.'Hacf5en Z.M

na Filed July 15'. 1922 Patented Aug. 23, 1927. g

UNITED DSTATESAVPATENT OFFICE.

ram) '1. Juneau,

'ro aurom'rro nLnc'rmo Wm FOREST PARK, ILLINOIS, ABSIGNOR, BY HESNE ASSIGNMEN'IE, ma, OF CHICAGO, ILLINOIS, A CORPORATION 01 DELI SEBVICE-OESEB'VING APPARATUS FOR AUTOMATIC TELEPHONE SYSTEMS.

Application filed July 15, 1982, Serial No. 575,888. mewe'd. June 26, 1986.

The present invention relates to service observing apparatus for automatic telephone systems, and has for its object the provlsion of new and improved circuit arrangements 5 whereby an o erator may connect with any one of severa lines ortrunks the trafliclon that line or trunk.

Another object is the provision of a new and improved impulse repeater which, when bridged across a calling line or trunk, repeats the interruptions produced by the calling subscribers calling device and does not appreciably interfere with the successful operation of the automatic switches conand observe trolled by the, calling subscriber.

The above pointed out objects, together with such others as are not specifically mentioned at this time, will be explained fully hereinafter, reference being bad to the accompanying drawings, comprising F1gs..1-5,

inclusive. In order to enable Figs. 1-4, in-

clusive, to be understood best, Figs. 1, 2, and

3 should be placed in order with the corresponding lines at the ends thereof in alignment, and Fig. 4 should be placed under Fig. 1, with the corresponding inter-connecting lines in alignment. When laid out thus, Figs. 1 and 4 represent certain equip- .ment associated with the observation oper- 0 'ators position; Fi 2 shows an observation connector on the istant end of the trunk terminating at the observation operatorsposition; and Fig. 8 represents a suflicient amount of automatic equipmentto enable a complete connection to be established between a calling and a called automatic line. Fig. 5 shows a desirable modification and -ma v be substituted for-Figs. 2 and 3..

Referring now particularly to Fig. 1, the

9 trunk which extends to the observation connector 00, Fig. 2, terminates in the contacts of the trunk key K, by means of which it may be connected with the operators circuit 0. Conductors -48, inclusive, of the oper-f ators circuit 0 may be multiplied to asv many of these trunk keys as desired, and consequently, there may be several trunks terminating in the operators osition, such. as the trunk comprising conuctors 49-52,

' inelusive.- .Jn practice, in a. large multioflice system, the operator is providedQwith one'trunk to each oilice in the system.

Referring now to Fig. '4, the so called minor. switch MS associated with the operators circuit 0, Fig. 1, is of simple-and well known construction and has an opernormally oil the associated banks, as shown,

while the wiper of the latter is normally on the first contact as shown. The adapting switch AS comprises a knob 84, which is secured to the rotatable EnOn-conductin member 85, and the associated wipers and contacts as shown. This switch may be rotated in a clockwise'direction' until the first wiper stands on the last bank contact, and I backagain to the starting point.

The observation connector 00, Fig. 2, is mechanically of the usual vertical and rotary type and accordingly its bank contacts are arranged in horizontal rows or levels. The observation connector 00', the selector D, Fig. 5, the selector D, and the connector E, Fig. 3, are mechanically identical with the observation connector 00.

The lineswitches O and C, Fig. 3, are of the well known rotary type in which the wipers have, no normal position and move in a forward direction only.

The automatic substations A and A i are of the usual type, having talking, signalling, and switch The line of substation A, the line conductors of the selector. D, and the line. conduccontrolling instrumentalities.v

tors of the connector E are cabled over to the distributing frame DF, 2. The bank contacts of the connector 0 also are cabled to the distributing frame DF, and the three sets of bank contacts shown are jumpered to the three pairs of line conductors shown on the other side of the frame. Preferably, only such trunks and lines as are t eught to be like y to req i o s e are cabled to the distributing frame, and

only those that are to be observed from time to time need be jumperedto the bank contacts of the connector 06. Similarly the contacts in the bank of the observation connector 00, Fig. 5, are cabled to the distributing frame DF and certain trunks such as the trunk leading to the selector D, are cabled to the other side of the frame.

It will be noted that the release trunk conductor also of the selector D' is carried over to the distributing frame DF', and

-'- that the connector OC' has a third wiper the receiver is removed at substation .A, a

circuit is closed over line conductors 202 and 204 for line relay 205 of the line switch C. Upon the energization of line relay 205, the line switch G operates in the usual manner to select an idle trunk, which trunk it will be assumed is the one extendin to the selector D. It will be understood: of course,

that the trunk selecting operation of the line switchC is necessary only in case the wipers of the switch are standing on a busy trunk when the call is initiated, and that the mechanical movement of the wipers is effected by the buzzer like action of stepping magnet 207- which magnet operates from ground on the test contacts of busy trunks. In any event, switching relay 206 energizes at the end of the trunk selecting movement, or immediately upon the energization of line relay 205 in case the line switch is standing on an idle trunk, and extends the calling line through to the selector D. The line and release relays of the selector D now energize in the usual manner and the latter, upon energizing, places ground upon the release trunk conductor'210 so as to establish the usual holding circuit for the line switch 0.

The calling subscriber now operates his calling device in accordance with the first digit in the desired numbergthereby producing a corresponding number of interruptions in the circuit of line relhy 208 of the selector D. In response to each of the resulting deenergizations of line relay 208, an impulse of current is delivered to vertical magnet 211 and as a result the wipers of the selector D are stepped up opposite the desired level of bankcontacts. Upon the termination of the vertical movement of the selector D the trunk selecting movement is initiated in the usual manner, whereupon aifidletr1mk--is selected, which trunk 1t will be assumed is the one extending to the connector E. That being the case, switching rela 214 of the selector D, upon energizing in t 1e usual manner at the end of the trunk selecting opera- I tion, extends the connection tothe connector E, whereupon line and release relays 221 and 2220f the connector'E energize. Upon energizing, release relay 222 places. round upon the release trunk conductor of t 1e connector E, thereby establishing the usual holding circuit for the line switch 0 and the selec-' tor D.

Most of the circuits of the connector E 1- have been omitted for the sake of simplicity,

only the line, release, and back bridge relays being shown. This is considered to be permissible for the reason that the operation of connectors is well known to those skilled v and the called subscribers bell is now rung in the usual mannerand, upon the response of the called subscriber the source of ringing current is removed and the called line is connected through to the windings of .back bridge relay 220 as shown by the dotted conductors. Back bridge relay 220, upon energizing, reverses the mcoming trunk conductors as regard their connection with the line relay 221. This is a standard operation and is used in certain cases to give supervision to toll operators and for operating meters and the like.

When the receiver is replaced at the called substation, back bridge relay 220 deenergizes and reverses the trunk conductors back to normal, and when the receiver is re laced at the calling substation the circuit 0 line relay 221 is opened. Upon deenergizing, line relay 221 opens the circuit of release relay 222, which relay deenergizes also, whereupon ground is removed from the release trunk conductor of the connector E and the switch is restored to normal in the usual manner.

.When ground is removed from the release It will be assumed now that the operator desiresto observe the traflic on the line of substatwn A. That being the case, she operates her key K thereby placing a bridge across trunk conductors 49 and 52, of the observation connector 00. This bridge includes the upper and lower contacts of the key K contacts of the key K, normally closed contacts controlled by spring 24 of re- 146 at armature 130, and at ari'nature 129' opens a point in the circuit of release magnet 155 and prepares acircuit for vertical magnet 156.

The operator now throws the key K in such a direction as to operate the right hand springs thereof, thereby substituting the calling device CD for the bridge including the impedance 10. The operator now manipulates the calling device CD in accordance with the bank level in which the line of substation A terminates in observation connector 00, thereby producing a corresponding number of interruptions in the circuit of line relays 106 and 107 of the observation connectorOC. Line relays 106 and 107 v are deenergized a corresponding number of times and, upon each deenerglzation, an 1mpulse of current is sent to vertical magnet" 156, the first impulse ofcurrent being trans-' mitted by way of the following path: from ground by way of armature 123 and its resting contact, armature 126 and its rest-ing contact," armature 129 and its working contact, resting contact of ofi normal spring 159 and said spring, relay 109, and vertical magnet 156 to battery. By the operation of vertical magnet 156, the wipers 144 and 146, are raised step by step until they stand opposite the desired level of contacts, which is the level in which contacts 147 and 149 are located. Relay 109 is energized in series with vertical magnet 156 and, being slow acting, retains its armature attracted throughout the vertical movement, thereby maintaining its own circuit and that of vertical magnet 156 intact after the oil normal springs shift as they do upon the first vertical step. At the end of the vertical movement, relay 109 deenergizes and transfers the operating circuit from the vertical to the rotary magnet.

The operator now manipulates the calling device CD in accordance with the digit necessary to step the wipers of the observation connector 00 into engagement with the bank contacts in which the line of substas tion A terminates. Each time line relays 106 and 107 deenergize in response to one of the second series of interruptions produced in their circuit, they send an impulse of currentto rotary magnet 157 over the following circuit: from ground by way of armature 123 and its resting contact, armature 126 and its resting contact, armature 129 and its working contact, normally open contacts controlled by off normal spring 159, armature 131 and its resting contact, relay 110', and rotary magnet 157 to battery. By the operation of rotary magnet 157, the

.wipers 144 and 146 are rotated step by step into engagement with the desired set of bank contacts, which, in this case, are the contacts 147 and 149. Relay 110 is energized in series with rotary magnet 157 and, being slow acting, retains its armature attracted through out the rotary movement, thereby .mainta1n-' ing Wiper 146 disconnected. As a further result of the energization of relay 110, it closes a circuit for relay 111 at armature 132. Relay 111, upon energizing, closes a looking circuit for itself at armature 135, and at armature 136 prepares a circuit for the linev relay of the operators circuit 0. At the end of the rotary movement, relay 110 deenergizes; connects up wiper 146 at armature 134; and at armature 133 closes a bridge across conductors 50 ,and '51 as follows: from conductor 51 by way of spring 112,

post 113, spring 114, armature 136 and itsworking contact, armature 133 and its resting contact, resistance 116, and the resting of armature 118 and said armature, to conductor 50. Line relay 9 of the operators circuit 0 now starts to energize. Also, assumingthe line of substationA to be idle, polarized relay 102 energizes in series with line relay 205 of line switch C and opens the circuit of line relay 9 of the operators circuit O at spring 112 or spring 114, depending upon the directions in which it is polarized. This occurs soon enough to prevent line relay 9 from operating release relay 8.

Line relay 205 of the line switch C does not energize at this time on account of the high resistance of relay 102 of the observation. connector 00.

The operator now throws her key K to the opposite or listening position, whereupon the calling device CD is disconnected from in bridge of the conductors 49 and 52, and the operators head set is bridged across said conductors 49 and 52. It will be noted that the impedance 11 is in series with one of the operators listening taps and that the operators receiver is shunted by the resistance 12. Theimpedance 11 is provided for the pur pose of preventing a heavy flow of voice currents so as not to materially affect trans mission on the line or trunk under observation. The resistance 12 is shunted around the operators receiver so as to enable her to listen to the dialling without hearing unline switch C is pulled up part way in the usual manner, upon ground being placed upon private normal conductor 203 by the connector which seizes the line of substation A by wa of the normal conductors extending to t e left of the line switch C. The connector now applies ringing current to the line of substation A in the usual manner.

The operator now hears the ringing current being applied to the called line. This ringing current, however, is not loud enough to cause the operator any discomfort owing to the resistance 12 being shunted around her receiver. The bridge, across the conductors of the called line, including relay 102 is high enough to prevent the ring-cut-ofi" relay of the calling connector from operating. lite lay 102, however, may operate in synchronism with the ringing current, but line relay 9 of the operators circuit O does not respond owing to the fact that, since its circuit is closed only when springs 112 and 114 are both in contact with post 113, its circuit is closed only a very short time during each swing oi? the armature of relay 102, which closure occurs at a time when the armature of relay 102 is moving rapidly. During each silent period, relay 102, of course, is energized in series with the ring-cut-otf relay of the connectors When the subscriber at substation A re- .sponds by removing his receiver, the ringcut-off relay oi"- the calling connector energizes in the usual manner and completes the talking circuit, whereupon the calling and called subscribers may converse. As a further result of the removal of the receiver at the calling substation, relay 102, being short circuited, deenergizes and closes a circuit for line relay 9 of the operators circuit 0. Line relay 9, upon energizing. closes a circuit for release relay 8. upon energizing, closes a circuit for the line lamp 1L armature 29, whereupon the said line lamp L becomes lighted, giving the operator answering supervision. in case she desires to listen in, the operator operates her push button it, thereby removing the resistance 12 from in shunt of her receiver. The operator does this so that she may ascertain whether or not the subscribers experience any difficulty in conversing with each other and if so she makes a note of the difiiculty. When the conversation is finished, the two subscribers hang up their receivers. Relay 102 in the connector 00 energizes and opens the circuit of line relay 9, whereupon line and release relays 9v and 8 deenergize and line lamp L becomes extinguished.

Assumin now that subscriber at substation A calls a subscriber, the subscriber at substation A for example, relay 102 of the observation connector 00 deenergizes owing to being shunted, when the receiver is re- Release relay 8,-

moved at the calling substation. Upondeenergizing relay 102, closes a circuit for line relay 9 of the operators circuit O. Line relay 9, upon energizing, closes a circuit for release relay 8 at armature 30. Release relay 8, upon energizing, prepares a circuit for relay 7 at armature 28 and at armature 29 places ground upon conductor 54:, thereby closing a circuit or the line lamp U, which lamp becomes lighted. As a further result of the ground potential being placed upon conductor 54:, a circuit is closed for magnet 7 8 of the tape recording device R by way of contacts on the push button P. Magnet 7 8, upon energizing, presses the sharp toothed wheel 7 9 into engagement with the tape 82. Relay 73 energizes in multiple with magnet 78 and closes a circuit for the compound wound motor M at armature 74. The motor M now rotates in such a direction as to drive the tape 82 toward the right, through the medium of the shaft 75 and the friction driving pulley 76. The idler pulley 81 is used to press the tape down on the driving pulley 76. Accordingly, the tape starts to move to the right and the saw toothed wheel 79 revolves as the tape passes under it and punches a dotted line in the tape, such as the one shown in the drawing. As a still further result of ground being placed on conductor 54:, relay 5 energizes in series with armature 21 and its resting contact and at armatures 2d and 25 shifts the two conductors controlled thereby over to the normally closed contacts controlled by armature 23.

In the meantime, the subscribers individual line switch G selects an idle first selector the selector D for example.

The calling subscriber now operates his calling device in accordance with the first digit in the desired number, thereby opening the circuit of the line relay of the selector D a corresponding number of times. In response to the deenergizations of the line relay of the selector l), the wipers of the selector are raised opposite the desired level of bank contacts after which an idle trunk, the trunk extending to the connector E for example, is selected in the usual manner. Each time the springs of the calling 'device at the" calling substation separate, a momentary high potential exists across the conductors Y of the calling line due to the self induction of line relay 208. This high potential causes the polarized relay 102 in the connector O0 to respond promptly. Each time the springs of the calling device at the calling substation close, relay 102 of the connector 00 is shunted and the armature is quickly restored to normal, the high potential produced at the break of the calling device springs hav ing subsided. This operation is' repeated each time an interruption is produced in the callin line. It may be stated that, while polarized relay 102 is energized in series with line relay 208 each time the calling device at substation A interrupts the circuit of the latter, the impedance of the bridge including the relay 102 is so high that the operation of line relay 208 is not noticeably affected.

Each time line relay 9 in the operators circuit Odeenergizes in response to the opening of its circuit by polarized relay 102 of the observation connector OC, it closes a circuit for slow acting .rela 7.- Relay 7 attracts its armature and, eing slow acting, retains it attracted throughout the series of deenergizations of line relay 9. Upon energizing, relay 7 closes a circuit for relay at armature 27 Relay 6, upon energizing, prepares a circuit for stepping magnet 65 of the minor switch MS, Fig. 4, at armature 26. As a further result of each deenergization of line relay 9, a circuit is closed for punch magnet 80 of the register- R in multiple with relay 7, by way of conductor 53 and contacts of the push button P. Punch magnet 80 is accordingly energized upon each deenergization of line relay 9-a11d punches a corresponding number of holes in the moving tape 82. Each time the circuit of relay 7 and punch magnet 80 is closed, a branch thereof extends by way of armature 31 of relay 4 and its resting contact, conductor 58, wiper 68, the first associated bank contact, lower contact and wiper of the adapting switch AS, ri ht hand contacts of the push button P and operating magnet 71 of the minor switch MS to batter Accordingly the operating magnet 71 of t e minor switch MS is; energized upon each deenergizatlon line relay 9 over the above circuit. By the operation of magnet 71, wiper 72 is advanced step by step until it comes into engagement with the bank contact corresponding to the number of deenergizations of the line relay 9, which number in turn correrpcnds to the first digit "dialled by the calling subscriber. At the end of the series of deenergizations of line relay 9, the said line relay comes to rest-in an energized condition,

leaving the circuit of slow acting relay 7 open. Relay 7, upon dcenergizing, opens the circuit of relay 6 at armature 27. Relay 6, however, being slow acting, retains its armature attracted for an interval. As a further result of the deenergization of relay 7, it closes at armature 27 and its resting contact the following circuit for stepping magnet 65 of the minor switch MS: from ground by way of armature 29 and its working contact, armature 27 and its resting contact, working contact of armature 26 and said armature, conductor 56, and stepping magnet 65 to battery: Stepping magnet 65, upon energizing, advances wiper 68 into engagement with the second associated bank contact. A moment later relay 6 deenergizes and opens the circuit of stepping magnet 65.

.minor switch MS is advanced into In response to the calling of the second digit in the desired number, the wipers of the connector E Fig. 3, are raised opposite the desired line in the usual manner. In the I operators circuit 0, line relay 9 is deenergized a number of times corresponding'to the digit called and at the first deenergization relays 7 and 6 energize one after the other as above described. At this time, magnet 80 of the register R punches a second series of holes in the tape 83, the number of which corresponds to the digitdialed. Also, upon each deenergization'of line relay 9, the stepping magnet of the minor switch MS is energized over a circuit which extends as previousl traced to wiper 68, and thence by way of t e second associated bank contact, contact and wiper of the adapting switch AS, second pair of contacts, from the right, of the push button P and the steppin magnet of the switch MS", to battery. y the operation of the stepping magnet of the s vitch MS, the associated wiper is advanced into engagement with. the contact corresponding to the second digit dialed. At the end of the series of deenergizations of relay 9, relays 7 and 6 fall back one after the other in the order named and send an impulse of current to stepping magnet 65 of the minor switch MS, whereupon the associated wiper 68 is advanced 'into engagement with the third associated bank contact.

When the calling device at the calling substation is turned for the third digit in the desired number, the wipers of the connector E are rotated into engagement with the set of banlccontacts in which the desired line terminates. In the operators circuit 0, line relay 9 is deenergized a number of times corresponding to digit dialed and, upon each deenergization, sends an impulse of current to the punch magnet 80 ofthe register R. Accordingly, a third series of holes is punched in the tape 82. Since wiper 68 is in engagement with its third associated bank contact, the stepping magnet of the minor switch MS is energized upon each deenergization of line relay 9 over a circuit with extends as traced to wiper 68 and thence by way of an easily seen path to stepping magnet of the minor switch MS As a result, the wiper of the engagement with the bank contact corresponding to the :third digit dialed.

The conductors extending from the bank contacts of the minor switches MSMS inclusive, are assumed to extend to a bank of lamps located so as to be seen by the op the minor switch as hereinbefore described, and sendlan impulse of current to stepping magnet 65' of MS. Upon energizing in response to this impulse of current, stepping magnet 65 advances the'wiper 68 into en.- gagement with the fourth associated bank contact. When this occurs, relay 4 energizes in series with relay 7 over the following circuit: from ground by way of the lower winding of relay 4, resting contact of armature 22 and said armature, resistance 59, conductor 55, upper wiper and associated contact of the adapting switch AS, fourth bank contact of the minor switch MS, wiper 68, conductor 58, resting contact of armature 31 and said armature, and relay 7 to battery. However, neither relay 7 nor magnet 80, which is in multiple with relay 7, is energized over this circuit on account of the high resistance 59. Upon energizing, relay 4 opens the circuit of slow acting relay 5 at armature 21.

Relay 5, however, being slow acting, retains its armature attracted for an interval. As a further result of the energization of relay 4, it closes a locking circuit for itself at armature 21 and, upon energizing a little further, opens its initial circuit at armature 22. As a further result of the energization of relay 4,it disconnects the operating conductor 53 from conductor 58 and,connects it to the upper winding of relay 3 at armature 31, and at armature 23, places ground on conductof 49 by way of armature 24 and its working contact, springs of the key K, the operators head set, other springs on the key K, and springs of the key K, at the same time disconnecti conductor 52. This holds line relay 1060f t e connector OC energized and permits line relay 107 to deenergize. Upon deener izing, line relay 107 closes a circuit for re ay 104 in multi le with resistance 116 at armature 125. elay 104, upon energizing, opens a point in the bridge across conductors 50 and 51, and prepares a locking circuit for itself in multiple with resistance 116 at armature 118. This does not open the bridge across conductors 50 and 51 on account of the multiple path through armatures 122 and 125. As a further result of the energization of relay 104, it places relay 103 in bridge of polarized relay.102 at armature 119. elay 103 is adjusted with very weak spring tension and, conse uently, is able to energize in multiple with t e calling subscribers loop. Upon ener izing, relay 103 again completes the bri ge across conductors 50 and 51 over a path which is exclusive of armatures 122 and 125. Relay 103, it may be stated, is of a resistance high enough to allow any line relay, such as line relay 220 of the connector E, to deenergize quickly in series with it.

Returning now to operators circuit 0, 7

sponds to the ringing of his bell by removing his receiver, the line wipers of the connector E are disconnected from the source of ringing current and are connected to the windings of back bridge relay 220, as shown by the dotted conductors. Back bridge relay 220, upon energizing over the calling subscribers loop, reverses the incoming line conductors as regards their connection with windings of line relay 221. In the observation connector 0C, relay" 103 deenergizes when the current falls to zero in the first direction and energizes again when the current builds up to maximum in the reverse direction. This is accomplished very quickly and results in a momentary opening of the circuit of line relay 9 in. the operators circuit 0. Line relay 9, upon deenergizing, operates magnet of the register R over conductor 53 in the usual manner. As a further result of the deenergization of line relay 9, a circuit is closed for the upper winding of relay 3 by way of conductor 53, armature 31 and its working contact, armature 19 and its resting contact, and upper winding of relay 3 to battery. Relay 3 energizes over this circuit far enough to operate the lightly adjusted armature 20 but not far enough to operate the more stifily adjusted arniatures 18 and 19. This adjustment is made easy due to the fact that the lay 3 pulls all the way up owing to the fact that current now flows through its upper and lower windings in series. Upon energizing fully, relay 3 disconnects the operating circuit from its own upper winding and extends it to relay 2 at armature 19, and at armature 18 closes acircuit for the lamp L. Lamp L, upon becoming lighted, signifies to the operator that the called man has answered.

By the above mentioned momentary energization of magnet 80 of the reglster R, a hole is punched in the tape therebyrecording the fact that the called subscriber has answered.

It will be noted that relay 104 n the observation connector OC is slow acting. This prevents the said relay 104 from deenergizing upon the momentary .deenerglzatlon of relay 103 as explained above.

Upon the termination of the conversation,

the two subscribers replace their receivers. Assuming that the subscriber at substation A replaces his receiver first, back bridge relay 220, upon deenergizing, reverses the line conductors of the connector E back to normal. When this occurs, relay 103 is again deenergized momentarily in the previously described manner and momentarily interrupts the circuit of line relay 9 of the operators circuit 0. When this occurs an impulse of current is delivered to magnet 80 of the register R whereupon another hole is punched in the tape 82. Also, an impulse of current is sent to relay 2 by way of the previously traced circuit to armature 19 of relay 3 and thence by way of the working contact of armature 19 and the normally closed contacts controlled by armature 16. Relay 2, upon energizing, closes a locking circuit for itself and opens its initial circuit at armature 16, and at armature 15 opens the circuit of the lamp L and closes the circuit of the lamp L. The lamp L becomes extinguished and the lamp L becomes lighted to inform the operator that one of the subscribers'has replaced his receiver.

When the receiver is replaced at the calling substation, the line relay 221 of the connector E deenergizes and polarized relay'102 in the connector OC energizes, in series with the line relay of the connector E and in multiple with relay 103, and opens the circuit of line relay 9 of the operators circuit 0. Line relay 9, upon deenergizing, opens the circuit of release relay 8 and closes the usual circuit for magnet 80 of the register R. Magnet 80, upon energizing, pierces the tape 82 again.

When the release of the connection occurs, due to the deenergization of release relay 222 of the connector E, which deenergization occurs before the deenergization of release relay 8 in the operators circuit 0, which relay has an exceptionally slow adjustment, switching relays 206 and 214 of the line switch 0 and the selector D, respectively, deenergize. When the upper and lower armatures of relay-206 break away from their working contacts, the circuit of relayx 102 in 'for re 82 stops moving.

whereupon the. said relay 102 deenergizes.

Almost immediately the upper and lower armatures of switching relay 206 of the line switch C come into engagement with their restin contacts, thereby closing a circuit ay 102 of the observation connector 00 in series with line relay 205. When this occurs, relay 102 energizes, comparatively slowly at this time, however, on account of its high impedance. The momentary deenergization of relay 102 at this time causes a momentary energization of line-relay 9 in the operators circuit.(). This energization is of suflicient'duration to permit magnet 80 of the register R to retract its armature sufliciently gong to skip a slight space on the tape 82 af er which it is attracted again. The momentary energization of relay 9, however, is not of sufiicient duration to completely saturate release relay 8 and; consequently, thesaid release relay 8, which was almost at the point of letting go when line relay 9 energized, retracts its armature al-' most immediately after the deenergization ofrelay 9. Upon deenergizing, release relay 8 opens the circuit of the magnet 80 of the register R and the circuit of relay 7 at armature 28, and at armature 29 opens the circuit of the line lamp, L and the locking circuit of relays 2, 3, and line lamp L becomes extinguished. As a further result of the removal of the ground potential from conductor 54, the circuit of relay 73 and magnet 78 of the register R is opened. Consequently, magnets 78 and 80 deenergize simultaneousl thus terminating the two records being made on the tape 82.

4,'whereupon the ture attracted for a slight interval, thereby .allowing time for tape 82 to be pulled out far enough to permit the complete record of the call to be exposed When relay 73 deenergizes, the circuit the motor M is opened, whereupon the tape As a further result of the deenergization of release relay 8 of the operators circuit 0, a circuit is closed for release magnet 66 of the minor switch MS,

release magnet 70 of the minor switch MS, and the release magnets of the minor switches MS and MS in multiple. The circuit of the release magnet of the minor switch MS is as follows: from ground by way of armature 29 of release relay 8 and its resting contact, conductor 57, off normal contacts 67, and release magnet 66 to battery. A branch of this circuit extends by way of a pair of contacts controlled by the push button P to oif normal contacts 69, and release magnet 70 of the minor switch MS to battery. This circuit extends also to the release magnets of the minor switches M3 and MS by way of their respective. associated 011' normal contact s. Upon the to the operators View.

energization of the release magnets of. the minor switches MS-MSF, inclusive, the wipers of the saidminor switches are restored to normal position, the circuit of the release magnets being opened by the off normal contacts when the associated wipers reach' normal position. The operators equipment is now completely restored to normal.

Assuming now that the subscriber at substation A is making a call and that be obtains the wrong number, the operator, who operates her push button P to remove the resistance 12 from in'shunt of her receiver after all the digits of the number have been dialed, learns from the conversation that something is wrong.

In order to converse with the calling subscriber and in order to be able to hold up the connection subsequently until the difficulty is located, the operator operates her talking key K. The upper pair of contacts of-the key K supply talking current to the operators head set. The next pair of contacts below, upon being closed, close a local circuit for line relay 9 through resistance 13 so as to prevent a false 0 eration as Wlll be explained subsequently. pring 11, upon being operated, pre ares the circuit for placing battery on con uctor 52 and disconnecting conductor 49 when the key K is restored subsequently. When the key K is restored, line relay 106 of the observation connector 0C deenergizes and places a shunt around the condenser which is between the right hand windings of the repeatingv c011 at armature 124 in series with armature 127, thereby holding the connection independent of the callin subscriber. The non-inductive resistance 13 7 is high enough to prevent the callin subsoribers transmltter from being robbe of too much talking battery so that the subscriber can converse with the test man when he comes in on the connection at the switch room as he does in the usual manner while searching for the defective switch. When this shunt is closed, relay 103 deenergizes and opens the-bridge across conductors 50 and 51 at armature 115. Line relay 9 in the operators circuit 0 does not deenergize, however, being held up over the local circuit including resistance 13. Relay 10 1 deenergizes in response to the deenergization of relay 103; disconnects relay 103 at armature 119; and at armature 118 opens its locking circuit and again closes the bridge across conductors 49 and 50.

Before having restored the key K, the operator observes, either on the tape 82 or on the bank of lamps controlled by the minor switches MSMS inclusive, the number called by the calling subscriber, and then asks him what number he desires. This is done so as to enable a check to be made to ascertain the cause of wrong numhere. In case the subscriber replies that he is diallin cated to t e operator the inference is that he has not properly dlalled the desired number, in which case the operator requests him to replace his receiver and call the number again. However, if he says that he is calling the number set up by the operators 1ndicating devices, the inference is that some one of the automatic switches through which the connection is extended has not operated properly. In this case, the operator requests the subscriber to wait a moment. She then restores the key K as above pointed out and gets in touch with an attendant at the auto matic exchange in any desired manner and tells him of the difficulty. The attendant immediately proceeds to trace the connection through and find out which switch has failed to respond properl He can easily do this because he has t e called number given to him by the operator. As soon-as the attendant has located the switch that is causing the trouble, he releases the connection by removing ground from the release trunk conductor of the switch iving the trouble and then makes that switcl i busy and informs the operator that he has fina number other than that indi- I ished. The attendant, of course, may make 0 such repairs and adjustments on the switch giving the trouble as may be necessary. When the connection is released by the attendant the line switch C immediatel picks out an idle first selector in the usua manner.

The operator, upon being informed by the attendant that he is through, again throws her key K, into listening posltion and requests'the calling subscriber to replace his receiver and dial the number over a ain. The operator then restores her ke to normal and releases the locking pu button P so as to replace the shunt around her receiver. When the key K is restored to normal, line relay 9 is again placed under control of the observation connector 06 and relay 107 in the observation connector 0C energizes owing to the circuit change roduced by the lower contacts of the key When the receiver is replaced at the calling substation, polarized relay 102 energizes in series with the line rela of the first selector which has been selecte by the line switch G and opens the circuit of line relay 9 of the operators circuit 0. Line relay 9, upon deenergizing restores conditions in the operators circuit to normal in the usual manner. Upon the deenergization of the line relay. of the first'selector 'to which the connection has been extended by the line switch C responsive to the release of the original connection by the attendant, the switch shaft steps up one step and is released again upon deenergization of the associated release relay.

When the receiver is removed at the calling substation the line switch C o erates in the usual manner to select an idle t selector and polarized relay 102 in the observation connector 00 deenergizes and closes the circuit of line relay 9 in the operators circuit 0. Line and release relays 9 and 8 now energize with the hereinbefore described results and the line lamp L becomes lighted.

The calling subscriber now proceeds to call scribers line or only first selector trunks,

etc., in one level of bank contacts. When this is done, theo erator may dial the observation connector C up opposite the desired level and then in on the first set of bank contacts in that level; observe the traific on the first trunk or line; and then operate her calling device for the digit one and ste the switch wipers over to the second set of ank contacts and so on to the tenth, observing the connected trunks or lines one by one as she sees fit.

It will be understood'that the o erator can dial the observation connector C u to the proper level and observe the tra c on any one of several first selector trunks depending upon which ones are jumpered over to the banks of the observation connector. The observing of traflic on a first selector trunk is very much similar to observing traffic on a subscribers line as hereinbefore described. The principal difference is that a trunk handles outgoing calls only and that a trunk is used much more frequently than a subscribers line.

In case the operator desires to observe .the traflic on a certain connector trunk, for example the trafiic on the connector E she dials the connector 00 up and around into en gagement with the proper set of bank contact-s. It is readily apparent that only two digits are called after the connector E is reached. In order to cause the last two digits called to be registered upon the minor switches MS and M which they are when a line or a first selector trunk is under observation, and in order for relay 3 in the operators circuit 0 to be 0 rated at the end of the last digit called, t e operator turns the adjusting switch AS in a clock-wise direction by means of the knob 84. This shifts the wipers of the switch forward until each one stands on the contact next in order. This allows the first digit received, or the one which operates the connector E vertically, to be received by the minor switch MS and the second digit received, or the onewhich operates the connector E to bring the wipers t ereof into engagement with the desired line, to 0 rate the last minorswitch MS. Then, at t e end of the last digit, the

wi er 68 comes into engagement with the third associated bank contact and closes a.

'circuit for the lower winding of rela 4 including the u per wiper of the ad uStin'g switch AS. (gtherwise the operations accompanying the observation of trafiic on a connector trunk are similar to the operations accom anying the observation of traific on a first se ector trunk. I

It is to be understood that in case-the observation equipment is used inconnection with a larger or smaller automatic system,

suitable changes may be made in the number or recordin minor switches such as the minor switch etc., and also that the adjusting switch AS may be suitably changed to meet the requirements.

7 The push buttons P and P are provided for the purpose of enabling the operator to disconnect either the. re ister R or the recording switches, or both, dependin upon what may be desired in any particu ar instance or on any particular occasion.

When the operator desires to release the observation connector OC, either because she wants to reoperate the said connector 0G to get on another'trunk or because she wants to connect her set with a trunk leadin to another ofiice, she restores the connectlng key K to normal, whereupon line relays 106 and ture 129 opens the circuit of rotary magnet 157 and closes a circuit for release ma et 155 by way of off normal spring 158 an its contact. elease magnet 155 now energizes, whereupon the shaft and wipers are restored to normal position in the usual manner, the circuit of release magnet 155 being opened at ofi normal spring 158 by the switch shaft when the latter reaches normal position.

Referring now particularly to Fig. 5, which drawing is best understood when placed to the right of Fig. 1 in place of Figs. 2 and 3, the operation of the observation connector 0C will now be explained. The circuits of the connector OC are very similar to the circuits of the connector OC, the principal difference being that the resistance 134 associated with relay 102 of the connector 0C is replaced by the condenser 12 in the connector 0C. This so changes the operation of the relay 102' that relays 103 and 104 of the connector 00 may be omitted. Another difference between the two circuits is thata third wiper is added and is connected as shown. This-wiper connects re- I spring 112 lay 111 to the release trunk conductor of the trunk under observation.

It will bev assumed now that the operator has stepped the observation connector 00 onto the trunk leading to the selector D". This is done, it will be understood, in the same manner as the connector 00 is stepped onto a desired set of contacts. It will be assumed now that the selector D is seized. This is accomplished by the seizing switch, which switch is similar to the line switch C, byplacing a bridge across the line conductors of the selector D and simultaneously placin ground on the release trunk conductor. when this occurs relay 111' energizes due to ground bein laced on the release trunk conductor 0 the selector D and closes a bridge across conductors 50 and 51 at armature 136, whereupon line and release relays 9 and 8 in the operators circuit 0 energize in the usual manner and perform the usual functions.

Each time the bridge across the line conductors of the selector D is opened by the calling subscribers calling device, the line relay of the selector D deenergizes in the usual manner and polarized relay 102 is energized quickly on account of the high potential discharge from the windings of the line relay of the selector D, and at either or 114, depending upon which way the relay is polarized, opens the circuit of line relay 9 of the operators circuit 0. The high potential which operates relay 102, and consequently the charge on the condenser 12, begins to subside almost immediately and entirely disappears before the springs of the calling dev1ce close again. The capacity of the condenser 12 is of such a value that relay 102 is not operated again by the minute discharge of the condenser 12' when the calling device springs again close. This allows only one opening in the circuit of line relay 9 for each opening in the bridge across the line conductors of the selector D and, as a result, line relay 9 responds to each opening of the bridge across the busy conductors of the selector D and produces the hereinbefore-descrioed results. This operation is repeated for each of the following two digits.

At the end of the third digit, relays 4 and .3 in the operators circuit 0 operate in the hereinbefore described manner. However, the momentary deenergization of line relay 107' of the connector 00, resulting from this operation is merely incidental and does not have any particular function.

When the reversal in the current flow occurs, upon the answering of the called subscriber, the condenser in series with the right hand windings of the repeating coil associated with the connector 0C as well as the condenser 12 in series with relay 102, is discharged when the springs of the back bridge relay of the connector, such as back budge rela 220 of the connector E, Fig. 3,

close tog'et er, and are charged in the option on the recording tape at the operators' position. When round is removed from release trunk con uctor by the connector to which the connection has been extended, the switching rela of the selector D and relay 111 of the o servation connector OC deenergize. Relay 111 upon deenergizing, opens the circuit of line relay 9 at armature 136 whereupon the operators equipment is restored to normal in the usual manner.

There 1s one record made on the recording tape at the operators osition when the observation connector 0 is used, that is not made when the observation connector 00 is used as Wlll new be explained. Assuming now that the selector D is seized by a line switch such as the line switch C, and that the calhng subscriber operates his calling device for the first digit in the usual manner, and that the selector D, upon finding an 1dle trunk, switches through on a trunk that. does not have the three conductors continuous. In this case, ground is not placed upon the release trunk conductor by the swltch ahead before the release relay of the selector D deenergizes and removes ground from the release trunk conductor at that pomt. Consequently, the switching relay of the selector D, the switching relay of the line swltch which seized the selector D, and relay 111 of the observation connector 0C deenergizesimultaneously. Relay 111, upon deener 1z1ng, opens the circuit of line relay 9 of t e operators circuit 0, whereupon punch magnet energizes. The switching relay of the selector D upon deencrgizlng, closes the usual release magnet c1rcu1t, whereupon the said selector D is restored to normal position in the usual manner. Almost immediately the relays of the hue switch operate again and seize the selec tor D again whereupon relay 111 energizes and again closes the circuit of line relay 9 of the operators circuit 0, whereupon line relay 9 energizes and punch magnet 80 deenergizes.

The record made by magnet 80 at this time, informs the observing operator or anyone who later inspects the tape of the fact that a trunk leading to a connector ofa' certain group is open. It can be readily seen that an open trunk causesthe record to be made because punch magnet 80 is held energized longer than usual at this time, and it can be ascertained which group of connectors contains the one having the open trunk by observing the digit dialled im' mediately before the open trunk was reached.

Theoperation accompanying the recording of the finding of an open trunk is substantially the same in case a subscribers line is under observation. In that case, of course, a private normal conductor, such as conductor 203 of the line switch C, is cabled back to the distributing frame DF' and the ground thereon operates relay 111 in the same manner as the round on release trunk conductor of the se ector D. The operations accompanying the use of the connector 0C, other than the exceptions noted, are identical with the operations when the observation connector 00 is used.

What is claimed is:

1. The combination, with an automatic switch operated by interruptions in a closed control circuit, of an impulse repeating relay bridged across said control circuit and inoperative as long as the circuit is closed, and a second circuit, said repeating relay being adapted to energize to control said second circuit each time said control circuit is interrupted to operate said switch.

2. The combination, with an automatic switch operated by interruptions in a closed control circuit, of an impulse repeating relay bridged across said control circuit, said relay being shunted as long as the circuit is closed, a second circuit controlled by the energization of said relay each time said control circuit is interrupted to operate said switch, and a second automatic switch controlled over said second circuit.

3. In combination, two relays connected in series with a battery, the first relay being of relatively high resistance and normally energized, the second relay-being of relatively low resistance and normally deenergized, means for shunting the high resistance relay to reverse the condition of said relays, and means for producing a series of interruptions in the shunt, the first relay energizing each time the shunt is opened and the second relay energizing each time the shunt is closed.

4. In combination, tworelays connected in series with a battery, the first relay being of relatively high resistance and normally energized, the second relay being of relatively low resistance and normally deenergized, means for shunting the high resistance relay to reverse the condition of said relays, means for producing a series of in- .terruptions in the shunt, the first relay energizing each time the shunt is opened. and

at said switch, a relatively high resistance relay temporarily connected in bridge of said line and normall energized, said line relay being normally d eenergized, means for closm a lowvresistance' bridge across said line w en the same is taken for use to energize said line relay, the high resistance relay emg shunted. out and deenergiz'ed, and means for producing interruptions in said low resistance bridge to operate said switch, said high resistance relay being energized at each interruption.

6. In a telephone system, a line terminating in an automatic switch, a line relayand a battery connected in series across said line at said switch, a relatively high resistance relay temporarily connected in bridge of said line and normally energized, said line relay being normally deenergized,-means for line when the same is taken for use to energize said line relay, the high resistance relay being shunted out and deenergized, means for producing interruptions in said low resistance bridge to operate said switch, said high resistance r-elay being energized at each interruption, a circuit closed by said high resistance relay when the same is de nergized, and an automatic switch controlled over said circuit in accordancewith the subsequent energizations of said high resistance relay.

7. In a telephone system means for connecting a calling and called line. means for reversingthe direction of current flow in the calling line when the called party responds and when he hangs up, anonpolar super visory relay bridged across the calling line, said relay being responsive inditferently to current flow in either direction, and signal ling means controlled by said relay when the same is momentarily deenergizcd by a current reversal through its winding.

8. In atelephone system, means for connecting a calling and called linev means for reversing the direct-ion of current flow in the calling line when the called party responds and when he hangs'up, a nonpolar supervisory relay bridged across the calling line, said relay being responsive indifferently to current flow in either direction, a signal operated by the momentary deenergizat-ion of said relay due to the current reversal through its winding when the called party answers, and a second signal operated by party hangs up.

' telephone system in tween a calling and called line is established by means of a series of automatic switches, of graphic .recordin apparatus temporarily associated with t e calling line. and intermediate controlling equipment'for operating said apparatus to make records indicating the duration of the call, the number of the called party, the time of answering and release by the called party, and the time of release by thecalling party.

11., The combinat'on. wit

' telephone system in which a connection be-.

tween acalling and called line is established by means of a series of automatic switches, of graphic recording apparatus temporarily as ociated with the calling line, and intermediate controlling equipment for operating said apparatus to record the operation of each switch and the answering and hanging up of the. called party, all timed with respect to the beginning and the end of the point call. I

12. The combination. with a telephone system in which a connection between a calling and. a called line is established by means of a series of automatic switches, of service observing equipment for recording the progrcss of the call, and means for automatically controlling said equipment to record the premature release of one of said Switches.

13, The combination, 7 system in which a connection between a calling and a called line is established bv means of a series of automatic switches. of service observing equipment comprising means for recording the progress of the call, means for associating said equipment with any switch in the series in order to intercept the call at any desired point, and means for settin said equipment portion of the call depending on the point at which the call is to be intercepted.

14. In atelephone system, a. line terminating in an automatic switch a. closed control circuit for said switch including a line relay connected in series with a battery, means for producing a series tions in said circuit to operate lay, an im also repeating relay bridged across said ine in series with a condenser. and an automatic switch controlled by said repeating relay.

15. In a telephone system, a main exraid line rewhich a connection beh an automatic with a telephone for a particular fractional 4 of interrupchange and a gilurality of branch exchanges, a plurality o difierent types of automatic switches in each branch exchange for completing connections between calling and called lines,an observation connector switch in each branch exchange having access to subscribers lines and said plurality of diffcrent types of automatic switches associated therewith, service observation equipment at said main exchange, trunk lines extending from the main. exchange to the observation connectors in the branch exchanges, and operator controlled means included in said main exchange for connecting said equipment to any trunk line and for operating the associated connector switch to connect with any subscribers such connector has access. o

16. In a telephone system, subscribers lines terminating in automatic switches, trunk lines of different orders terminating in automatic switches of different orders, means whereby a calling subscriber operates his associated switch and an automatic switch of each order to complete a connection to a called line, service observing equipment, a connector'switch having access to said subscribers lines and said trunk lines, and means for operating said connector to connect said equipment with any trunk line in use so as to intercept the call at any desired 17. In a telephone system, a series of automatic switches for establishing a connection between a calling and a called line, service observation equipment, a connector switch associated with said equipment having access to said-subscribers lines and all of said switches, and means nector swit h-to connect said equipment with either of said lines-or any of said switches.

18. In a telephone system, a pluralityot trunk lines, each of said plurality terminating inan automatic switch, operators equipment, a recording device associated with said equipment 1' or making records indicating the duration of a call. the number-of the called party," the time of'answering of the called party, and calling parties, means for associating said equipment with a trunk line of said plurality, means for seizing said trunk line, means controlled over said seized trunk line Y for operating the associated automatic switch to extend a connection to a called line, and means operative responsive to the seizure of said trunk line for automatically starting said device.

19. In a telephone system, a plurality of trunk lines, each of said plurality terminating in an automatic switch, operators equipment, a recording device associated with said equipment for making records indicating the duration at a call, the number ofthe called party, the time of answering oLthe line or switch to whichfor operatlng said concalled party, and the time of release by the called and calling parties, means for associating said equipment with a trunk line of said plurality, means for seizing said to the calling party hanging n his receiver for' automatically stopping sai device, and means for maintaining said device operated a short interval after the replacement of the calling subscribers receiver in order to allow the recording device to move far enough to be easily read.

20. In a telephone system, a plurality of trunk lines, each of said plurality terminating in any automatic switch, operators equipment, means for associating said operators equipment with any one of said trunk lines, subscriber controlled means for seizing one of said trunk lines and for operating the associated automatic switch to extend a connection to a called line, means included in said equipment operated responsive to such seizure for notifying the operator that a call is in progress over the connected trunk line, and a registering device associated with said equipment operated in synchronism with said associated automatic switch.

21. In a telephone system, a plurality of trunk lines, each of said plurality terminating in an automatic switch, operators equipment, means for associating said operators equipment with any one of said trunk lines, subscriber controlled means for seizing one of said trunk lines and for operating the associated automatic switch to extend a connection to a called line, means included in said equipment operated responsive to such "seizure for notifymg the operator that a call is in progress over the connected trunk line,

a registering device associated with said equipment operated in synchronism with said associated automatic switch, and operator controlled means for disconnecting said device from said equipment.

22. In a telephone system, a plurality of trunk lines, each of said Iplurality terminating in an automatic switc operators equipment, means for associating said operators equipment with any one of said trunk lines, subscriber controlled means for seizing one of said trunk lines and for operating'the associated automatic switch to extend a connection to a called line, means included in said equipment operated responsive to such seizure for notifying-the operator that a call is in progress over the connected trunk line, a registering device associated with said equipment operated in synchronism with said associated automatic switch, first and second visual signals at said equipment, and means operated responsive to the called party answering for lighting said first signal and for operating said device, said last means operated again responsive to either party hanging up his receiver for lighting said second signal and for o erating said device.

23. In a telep lone system, a pluralit of trunk lines, each of said plurality terminating in an automatic switch, operators equipment, means for associating said operators equipment with any one of said trunk lines, subscriber controlled means for seizing one of said trunk lines and for operating the as sociated automatic switch to extend a connection to a called line, means included in said equipment operated responsive to such is l seizure for notifymg the operator that a call I is in progressover the connected trunk line, a registering device associated with said equipment operated in synchronism with said associated automatic switch, subscriber controlled means for releasing said associated automatic switch, and operator controlled means for preventing said release.

24. In a telephone system, a plurality of subscribers lines and trunk lines of different orders terminating in an intermediate distributing frame, an automatic switch, jumpers on said frame connecting said subscribers lines and trunk lines with the banks of said switch, operators equipment, means included in said operators equipment for operating said switch to connect toany one of said subscribers lines or any one of said trunk lines, and means associated with said operators equipment for obrerving the progress of a call on said connected line and for making a permanent record of such call wlzen the same 18 made.

25. In a telephone system, a plurality of subscribers lines and trunk lines of differentv orders terminating in an intermediate distributing frame, an automatic switch, jumpers on said frame connecting said subscribers" lines and trunk lines with the banks of said switch, operators equipment, means included in said operators equipment for operating said switch to connect to any one of, said subscribers lines or anyone of said trunk lines, means associated with said operators equipment for observing the progress of a call on said connected line and for making subscribers" lines or any one off said trunk lines, means associated with said operators equipment for observing the progress of a call on said connected line and for making a permanent record of such call when the same is made, and said first means also adapted to operate said switch'from said connected line to successive lines without releasing said switch in order to observe the calls on such successi re lines.

27. in a telephone system, means including series of automatic switches for connecting a calling and called line, registering apparatus for recording the digits in the called number, an observation connector, a supervisory relay and a pair of line relays in said connector, means for operating said line relays in accordance with one or more digits to operate said connector to connect said apparatus with a switchot said series, and means controlled by said registering apparatus responsive to the last di it in the number for operating the first or said line relays and not the second to cause said supervisory relay to be connected in bridge of the calling line.

28. In a telephone system, means including a series of automatic switches for connecting a calling and called line, registering apparatus for recording the digits in the called number, an observation connector, a supervisory relay and a pair of line relays in said connector, means for operating sald line relays in accordance with one or more digits to operate said connector to connect said apparatus with a switch of said series, means controlled by said registering apparatus responsive to the last digit in the number for operating the first of said line relays and not the second to cause said supervisory relay to be connected in bridge of the calling line, and operator controlled means for operating the second of said line relays and not the first to prevent the calling subscriber from releasing the switch with which said apparatus is connected.

v 29. In a telephone system, a series of automatic switches for establishin a connection between a calling and a ca led line, service observation equipment, an observation connector associated with said equipment, means included in said equipment for operating said connector to connect said equipment with any switch in said series, said equipment comprising two indicating means to record the progress of a call, one indicating means being a series of switches to operate lamps to indicate the digits incense dialled establishing a connection, the other lilldlCfililn means being a register to record the digits dialled .onWa-rtape, and

means in said equipment for disconnecting 31. In a telephone system, a series of automatic switches for establishing a connection between a 'ca'llingand a called line, said series comprising a non-numerical switch, a single digit numerical switch'and a two digit numerical switch, service observation equipment comprising visual indicating means, there being one indicating means provided for each digit of the called number, means for associating said equipment with any one 'ot'said switches, and means for setting said equipment to use only a certain number of said indicating means dependent upon which switch said equipment is associated with.

32. 'The combination with a circuit having a source of current therein, of a second circuit, a relay having a winding in said second circuit, a condenser in said second circuit, means for altering the flow of current in said first circuit, the change of current in said first circuit inducing a current in said second circuit which charges the condenser and flows through said winding, said relay responding to said induced current, and means controlled by said relay.

33. The combination with a line circuit havin a source of current therein. of a second circuit, a relay having a winding in said second circuit, a condenser in said second circuit arranged to be charged by the source of current in said line, means for changing the flow of current in said line, the change of current in the line circuit in ducing a current in said second circuit which charges the condenser and flows through said winding, said relay responding to the induced current, and a variably operable switch actuated by said relay.

In witness whereof, I hereunto subscribe my name this 7th day of July, A. 1)., 1922.

FRED T. MADSEN. 

